1. Field of the Invention
The present invention generally relates to magnetic storage devices, and more particularly, to a magnetic storage device having a head suspension supporting a head slider.
2. Description of the Related Art
In a magnetic disk device that is a typical magnetic storage device, a head slider having an element for recording and regeneration is supported by a head suspension. In addition, the head slider floats stably at a minute height from a surface of a rotating magnetic disk, so that information is recorded and regenerated.
FIG. 1 is a perspective view of a head suspension of the related art. Referring to FIG. 1, a recording datum is transmitted from a central processing unit (CPU) of a personal computer (PC) connected to a magnetic disk device to a head IC 112 on a head suspension 100 through a main IC 111.
The recording datum is converted to an electric current signal by the head IC 112 so as to be transmitted to a minute element 114 for recording of a head slider 113. The recording datum as the electric current signal is converted to a magnetic field signal by a conductive coil of the element 114 for recording, so as to be recorded to a magnetic disk (not illustrated) applied by the magnetic field signal. The datum recorded to the magnetic disk is regenerated by a minute element 115 for regenerating of the head slider 113 so as to be transmitted to the CPU by a process reversing the process for recording.
Meanwhile, the head slider 113, fixed to a head end of the head suspension 100, generates a floating force by using air flow based on rotation of the magnetic disk, because of a configuration of an air bearing surface 113-1 facing the magnetic disk.
On the other hand, the head suspension 100, supporting the head slider 113, generates a load force pushing the head slider 113 to the magnetic disk by a spring part 100-3 of the head suspension 100. The head slider 113 floats stably at a minute floating height from the surface of the magnetic disk because of a balance of the floating force and the load force.
The load force is a spring load of the head suspension 100. A base part 100-1 of the head suspension 100 is a cantilever fixed to an end part 121-1 of a head arm 121. In addition, the head suspension 100 is bent to the side of the magnetic disk at a bending position 100-4 of the spring part 100-3 between the base part 100-1 and a head slider fixing part 100-2 situated at the head end of the head suspension 100. The load force is determined by a product of the spring constant and the bent amount of the above mentioned spring part 100-3.
The bent amount of the above mentioned spring part 100-3 is defined as a deformation amount of the head slider fixing part 100-2 from a state where no floating force is applied to a state where the floating force is applied to the head slider 113 so as to float. Therefore, for instance, as the floating height increases, the deformation amount of the head slider fixing part 100-2 increases so as to increase the bent amount of the spring and increase the load force. The direction of the deformation is the floating direction of the head slider 113. The direction of the deformation is defined as the Z directions in FIG. 1.
On the other hand, the floating force is generated by pressure of an air flow that flows in the head slider 113 based on the rotation of the magnetic disk. Therefore, in a case where the floating height of the head slider 113 is low, the pressure of the air flow increases so that the floating force increases. In addition, as the floating height increases, the pressure of the air flow decreases so that floating force is decreased.
Therefore, the head slider 113 floats stably with a floating height balanced between the load force and the floating force. The floating height is a distance from the surface of the magnetic disk to a head end of a magnetic pole of the element 114 for recording of the head slider 113.
Meanwhile, recently, higher density recording has been in demanded. Because of this, it has been attempted to position the air bearing surface of the head slider 113 as close to the surface of the magnetic disk as possible, in order to secure a regeneration output. The floating height of the head slider 113 is reduced to approximately 30 nm.
On the other hand, as the frequency of a signal treated by an information processing device becomes high, it is required for the recording frequency of a signal recorded to the magnetic disk to have a value that exceeds the present 200 MHz, for example to rise to approximately 500 MHz. Thus, as the recording frequency increases, an exothermic amount of energy from a conductive coil of the element 114 for recording increases due to a high frequency eddy current lost, for example. In addition, an exothermic amount of energy of the head IC 112 disposed to the head suspension 100 also increases.
The temperature of the head suspension 100 itself increases due to the above mentioned exothermic amounts of energy so that the head suspension 100 extends due to thermal expansion. In this case, assuming that the floating force is not applied to applied to the head slider 113, the head slider 113 itself extends in a direction approaching the surface of the magnetic disk. Therefore, the bent amount (the deformation amount in a Z direction) of the head suspension 100 from the above state to the state where the floating force is applied to the head slider 113 increases. As a result of this, the load force of the head suspension 100 increases so that the balance between the load force and the floating force of the head slider 113 is lost and the floating height decreases to the height where the balance is regained.
As described above, since the floating height of the head slider 113 is minute, the head slider 113 may come in contact with the surface of the magnetic disk. In a case where the head slider 113 comes in contact with the surface of the magnetic disk, a signal waveform regenerated by the element for regenerating becomes abnormal. Hence, a protection layer of the surface of the magnetic disk may be destroyed or the air bearing surface of the head slider may be destroyed.